Align reactRoot config between server and webpack config (vercel#34328)

### Changes

* node server and webpack should share the same logic: auto detect react 18 and enable `reactRoot`
* fallback `_error` should use functional document if concurrent rendering is enabled

### Test

* Remove the hard code `reactRoot: true` in test suite
* Test some react-18 test suite with nodejs runtime

packages/next/build/webpack-config.ts

@@ -2,7 +2,6 @@ import ReactRefreshWebpackPlugin from 'next/dist/compiled/@next/react-refresh-ut
 import chalk from 'next/dist/compiled/chalk'
 import crypto from 'crypto'
 import { stringify } from 'querystring'
-import semver from 'next/dist/compiled/semver'
 import { webpack } from 'next/dist/compiled/webpack/webpack'
 import type { webpack5 } from 'next/dist/compiled/webpack/webpack'
 import path, { join as pathJoin, relative as relativePath } from 'path'
@@ -15,7 +14,6 @@ import {
   MIDDLEWARE_ROUTE,
 } from '../lib/constants'
 import { fileExists } from '../lib/file-exists'
-import { getPackageVersion } from '../lib/get-package-version'
 import { CustomRoutes } from '../lib/load-custom-routes.js'
 import {
   CLIENT_STATIC_FILES_RUNTIME_AMP,
@@ -52,6 +50,7 @@ import type { Span } from '../trace'
 import { getRawPageExtensions } from './utils'
 import browserslist from 'next/dist/compiled/browserslist'
 import loadJsConfig from './load-jsconfig'
+import { shouldUseReactRoot } from '../server/config'
 
 const watchOptions = Object.freeze({
   aggregateTimeout: 5,
@@ -337,21 +336,7 @@ export default async function getBaseWebpackConfig(
     rewrites.afterFiles.length > 0 ||
     rewrites.fallback.length > 0
   const hasReactRefresh: boolean = dev && !isServer
-  const reactDomVersion = await getPackageVersion({
-    cwd: dir,
-    name: 'react-dom',
-  })
-  const isReactExperimental = Boolean(
-    reactDomVersion && /0\.0\.0-experimental/.test(reactDomVersion)
-  )
-  const hasReact18: boolean =
-    Boolean(reactDomVersion) &&
-    (semver.gte(reactDomVersion!, '18.0.0') ||
-      semver.coerce(reactDomVersion)?.version === '18.0.0')
-
-  const hasReactRoot: boolean =
-    config.experimental.reactRoot || hasReact18 || isReactExperimental
-
+  const hasReactRoot = shouldUseReactRoot()
   const runtime = config.experimental.runtime
 
   // Make sure reactRoot is enabled when react 18 is detected
@@ -360,11 +345,7 @@ export default async function getBaseWebpackConfig(
   }
 
   // Only inform during one of the builds
-  if (
-    !isServer &&
-    config.experimental.reactRoot &&
-    !(hasReact18 || isReactExperimental)
-  ) {
+  if (!isServer && config.experimental.reactRoot && !hasReactRoot) {
     // It's fine to only mention React 18 here as we don't recommend people to try experimental.
     Log.warn('You have to use React 18 to use `experimental.reactRoot`.')
   }

packages/next/build/webpack/loaders/next-middleware-ssr-loader/render.ts

@@ -72,6 +72,7 @@ export function getRender({
     webServerConfig: {
       extendRenderOpts: {
         buildId,
+        reactRoot: true,
         runtime: 'edge',
         supportsDynamicHTML: true,
         disableOptimizedLoading: true,

packages/next/server/config.ts

@@ -1,9 +1,10 @@
-import chalk from '../lib/chalk'
-import findUp from 'next/dist/compiled/find-up'
 import { basename, extname, relative, isAbsolute, resolve } from 'path'
 import { pathToFileURL } from 'url'
 import { Agent as HttpAgent } from 'http'
 import { Agent as HttpsAgent } from 'https'
+import semver from 'next/dist/compiled/semver'
+import findUp from 'next/dist/compiled/find-up'
+import chalk from '../lib/chalk'
 import * as Log from '../build/output/log'
 import { CONFIG_FILES, PHASE_DEVELOPMENT_SERVER } from '../shared/lib/constants'
 import { execOnce } from '../shared/lib/utils'
@@ -653,6 +654,11 @@ export default async function loadConfig(
       )
     }
 
+    const hasReactRoot = shouldUseReactRoot()
+    if (hasReactRoot) {
+      userConfig.experimental.reactRoot = true
+    }
+
     if (userConfig.amp?.canonicalBase) {
       const { canonicalBase } = userConfig.amp || ({} as any)
       userConfig.amp = userConfig.amp || {}
@@ -698,6 +704,19 @@ export default async function loadConfig(
   return completeConfig
 }
 
+export function shouldUseReactRoot() {
+  const reactDomVersion = require('react-dom').version
+  const isReactExperimental = Boolean(
+    reactDomVersion && /0\.0\.0-experimental/.test(reactDomVersion)
+  )
+  const hasReact18: boolean =
+    Boolean(reactDomVersion) &&
+    (semver.gte(reactDomVersion!, '18.0.0') ||
+      semver.coerce(reactDomVersion)?.version === '18.0.0')
+
+  return hasReact18 || isReactExperimental
+}
+
 export function setHttpAgentOptions(
   options: NextConfigComplete['httpAgentOptions']
 ) {

packages/next/server/dev/next-dev-server.ts

@@ -940,7 +940,9 @@ export default class DevServer extends Server {
     // Build the error page to ensure the fallback is built too.
     // TODO: See if this can be moved into hotReloader or removed.
     await this.hotReloader!.ensurePage('/_error')
-    return await loadDefaultErrorComponents(this.distDir)
+    return await loadDefaultErrorComponents(this.distDir, {
+      hasConcurrentFeatures: !!this.renderOpts.runtime,
+    })
   }
 
   protected setImmutableAssetCacheControl(res: BaseNextResponse): void {

packages/next/server/load-components.ts

@@ -34,8 +34,14 @@ export type LoadComponentsReturnType = {
   ComponentMod: any
 }
 
-export async function loadDefaultErrorComponents(distDir: string) {
-  const Document = interopDefault(require('next/dist/pages/_document'))
+export async function loadDefaultErrorComponents(
+  distDir: string,
+  { hasConcurrentFeatures }: { hasConcurrentFeatures: boolean }
+) {
+  const Document = interopDefault(
+    require(`next/dist/pages/_document` +
+      (hasConcurrentFeatures ? '-concurrent' : ''))
+  )
   const App = interopDefault(require('next/dist/pages/_app'))
   const ComponentMod = require('next/dist/pages/_error')
   const Component = interopDefault(ComponentMod)

test/integration/react-18/test/index.test.js

@@ -1,7 +1,6 @@
 /* eslint-env jest */
 
 import { join } from 'path'
-import fs from 'fs-extra'
 
 import {
   File,
@@ -57,12 +56,11 @@ async function getDevOutput(dir) {
 
 describe('React 18 Support', () => {
   describe('Use legacy render', () => {
-    beforeAll(async () => {
-      await fs.remove(join(appDir, 'node_modules'))
+    beforeAll(() => {
       nextConfig.replace('reactRoot: true', 'reactRoot: false')
     })
     afterAll(() => {
-      nextConfig.replace('reactRoot: false', 'reactRoot: true')
+      nextConfig.restore()
     })
 
     test('supported version of react in dev', async () => {
@@ -75,15 +73,17 @@ describe('React 18 Support', () => {
       expect(output).not.toMatch(USING_CREATE_ROOT)
     })
 
-    test('suspense is not allowed in blocking rendering mode (prod)', async () => {
+    test('suspense is not allowed in blocking rendering mode', async () => {
+      nextConfig.replace('withReact18({', '/*withReact18*/({')
       const { stderr, code } = await nextBuild(appDir, [], {
-        nodeArgs,
         stderr: true,
       })
-      expect(code).toBe(1)
+      nextConfig.replace('/*withReact18*/({', 'withReact18({')
+
       expect(stderr).toContain(
         'Invalid suspense option usage in next/dynamic. Read more: https://nextjs.org/docs/messages/invalid-dynamic-suspense'
       )
+      expect(code).toBe(1)
     })
   })
 })
@@ -119,56 +119,58 @@ describe('Blocking mode', () => {
   )
 })
 
-describe('Concurrent mode in the edge runtime', () => {
-  beforeAll(async () => {
-    nextConfig.replace("// runtime: 'edge'", "runtime: 'edge'")
-    dynamicHello.replace('suspense = false', `suspense = true`)
-    // `noSSR` mode will be ignored by suspense
-    dynamicHello.replace('let ssr', `let ssr = false`)
-  })
-  afterAll(async () => {
-    nextConfig.restore()
-    dynamicHello.restore()
-  })
+function runTestsAgainstRuntime(runtime) {
+  describe(`Concurrent mode in the ${runtime} runtime`, () => {
+    beforeAll(async () => {
+      nextConfig.replace("// runtime: 'edge'", `runtime: '${runtime}'`)
+      dynamicHello.replace('suspense = false', `suspense = true`)
+      // `noSSR` mode will be ignored by suspense
+      dynamicHello.replace('let ssr', `let ssr = false`)
+    })
+    afterAll(async () => {
+      nextConfig.restore()
+      dynamicHello.restore()
+    })
 
-  runTests('`runtime` is set to `edge`', (context) => {
-    concurrent(context, (p, q) => renderViaHTTP(context.appPort, p, q))
+    runTests(`runtime is set to '${runtime}'`, (context) => {
+      concurrent(context, (p, q) => renderViaHTTP(context.appPort, p, q))
 
-    it('should stream to users', async () => {
-      const res = await fetchViaHTTP(context.appPort, '/ssr')
-      expect(res.headers.get('etag')).toBeNull()
-    })
+      it('should stream to users', async () => {
+        const res = await fetchViaHTTP(context.appPort, '/ssr')
+        expect(res.headers.get('etag')).toBeNull()
+      })
 
-    it('should not stream to bots', async () => {
-      const res = await fetchViaHTTP(
-        context.appPort,
-        '/ssr',
-        {},
-        {
-          headers: {
-            'user-agent': 'Googlebot',
-          },
-        }
-      )
-      expect(res.headers.get('etag')).toBeDefined()
-    })
+      it('should not stream to bots', async () => {
+        const res = await fetchViaHTTP(
+          context.appPort,
+          '/ssr',
+          {},
+          {
+            headers: {
+              'user-agent': 'Googlebot',
+            },
+          }
+        )
+        expect(res.headers.get('etag')).toBeDefined()
+      })
 
-    it('should not stream to google pagerender bot', async () => {
-      const res = await fetchViaHTTP(
-        context.appPort,
-        '/ssr',
-        {},
-        {
-          headers: {
-            'user-agent':
-              'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36 Google-PageRenderer Google (+https://developers.google.com/+/web/snippet/)',
-          },
-        }
-      )
-      expect(res.headers.get('etag')).toBeDefined()
+      it('should not stream to google pagerender bot', async () => {
+        const res = await fetchViaHTTP(
+          context.appPort,
+          '/ssr',
+          {},
+          {
+            headers: {
+              'user-agent':
+                'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36 Google-PageRenderer Google (+https://developers.google.com/+/web/snippet/)',
+            },
+          }
+        )
+        expect(res.headers.get('etag')).toBeDefined()
+      })
     })
   })
-})
+}
 
 function runTest(mode, name, fn) {
   const context = { appDir }
@@ -200,6 +202,9 @@ function runTest(mode, name, fn) {
   })
 }
 
+runTestsAgainstRuntime('edge')
+runTestsAgainstRuntime('nodejs')
+
 function runTests(name, fn) {
   runTest('dev', name, fn)
   runTest('prod', name, fn)

test/integration/react-18/test/with-react-18.js

@@ -1,8 +1,4 @@
 module.exports = function withReact18(config) {
-  if (typeof config.experimental.reactRoot === 'undefined') {
-    config.experimental.reactRoot = true
-  }
-
   config.webpack = (webpackConfig) => {
     const { alias } = webpackConfig.resolve
     // FIXME: resolving react/jsx-runtime https://github.com/facebook/react/issues/20235

test/integration/react-streaming-and-server-components/app/next.config.js

@@ -6,7 +6,6 @@ module.exports = withReact18({
   },
   pageExtensions: ['js', 'ts', 'jsx'], // .tsx won't be treat as page,
   experimental: {
-    reactRoot: true,
     serverComponents: true,
     runtime: 'edge',
   },